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The original JA Purity template was provided from JoomlArt.com as a zip but the latest files have been installed along with Joomla. The relevant files, logo.gif (used for PNG transparency problems), logo.png and template.css, can be found in templates/ja_purity. If you've been following the tutorial, you can download a tutorial version of the template that installs to the templates/my_japurity folder. Inside the folder of the template, the files are located as follows:

<location of template>/
css/
template.css
images/
logo.gif
logo.png

Replacing the Logo

Create a new image, width: 207 pixels , height: 80 pixels using any graphics editor such as Gimp.

Save the image as both a PNG and a Gif to the template images directory. Make sure you overwrite the existing logo.gif and logo.png files.

Edit, Save, Test till you are satisfied with your new logo.

Changing the Logo Size

You can edit the CSS file directly in your choice of plain text editors such as VI or Notepad or you can use the CSS Editor provided in the Joomla Administration area.

To use the Joomla editor log into the Administration area of your site